The last known Galapagos tortoise, Lonesome George, was estimated to be 100 years old when he died in 2012, and researchers who compared George's genome with that of a different species of tortoise in the Aldabra Atoll discovered that both tortoises carried 12 copies of a gene that enables immune cells to kill invading or abnormal cells. Among the other findings, reported in Nature Ecology & Evolution, are an especially efficient variant of a DNA-repairing enzyme and duplicate genes associated with tumor suppression.